Power lift means affording depth regulation of tractor propelled implements



May 25, 1954 w. F. STREHLOW 2,679,199 POWER LIFT MEANS AFFORDING DEPTH REGULATION OF TRACTOR PROPELLEID IMPLEMENTS Filed May 26, 1948 6 sheets sheet l May 25, 1954 w. F. STREHLOW 2,679,199

POWER LIFT MEANS AFFORDING DEPTH REGULATION OF TRACTOR PROPELLED IMPLEMENTS Filed May 26, 1948 6 Sheets-Sheet 2 y 25, 1954 w. F. STREHLOW 2,679,199

POWER LIFT MEANS AFFORDING DEPTH REGULATION OF TRACTOR PROPELLED IMPLEMENTS Filed May 26, 1948 6 Sheets-Sheet 3 a mo Lima/L 5 SXMMQAM 1% W14. La

- m/mw y 5, 1954 w F. STREHLOW 2,679,199

POWER LIFT MEANS AFFORDING DEPTH REGULATION OF TRACTOR PROPELLED IMPLEMENTS Filed May 26, 1948 6 Shee ts-Sheet 4 y 25, 1954 w. F. STREHLOW 2,679,199

POWER LIFT MEANS AFFORDING DEPTH REGULATION OF TRACTOR PROPELLED IMPLEMENTS Filed May 26, 1948 6 Sheets-Sheet 5 495 mm 56 I83 2/9 Patented May 25, 1954 POWER LIFT MEANS 'AFFORDING DEPTH REGULATION OF TRACTOR PROPELLED IMPLEMENTS Walter F. Strehlow, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application May 26, 1948, Serial No. 29,234

12 Claims. 1

This invention relates generally to the control of implements propelled by any suitable selfpowered vehicle, hereinafter termed a tractor, and is more particularly concerned with the provision of apparatus for selectively positioning and/or controlling one or more such implements, as desired, certain of the features hereinafter shown and described being disclosed and claimed in my copending application Ser. No. 27,928, filed May 19, 1948, now Patent No. 2,611,245.

In operating the various types of tractor attached implements, it is now common practice to employ a hydraulic system comprising a pump means driven by power derived from the tractor engine, a ram unit receiving pressure liquid from the pump means and operatively connected with the implement to raise or lower same, and a manuallyactuable valve means for controlling operation of the ram unit. In general, the hydraulic systems heretofore employed have been fairly satisfactory for effecting the usual raising or lowering movements of an implement. However, these systems have not proven entirely satisfactory in that they do not aiford an infinite number of rates at which an implement can be either raised or lowered and as a result it is diflicult, if not impossible, to effect increment adjustment of implement position and/or to increase the rate of implement lift as a function of a variable,

such as draft force. Consequently, none of these known systems has proven particularly successful as a means for automatically regulating the depth of penetration of a soil working implement since, for the reasons previously stated, their responsiveness to variations in draft force is conducive to an excessive degree of hunting.

It is, therefore, an object of this invention to provide an improved control system for tractor propelled implements wherein parts are constructed and combined for coaction in a manner affording an infinite number of rates at which the implement can be raised or lowered, and/or affording an'increment adjustment of implement position.

Another object of the present invention is to provide a tractor with an improved control system and hitch means combined for readily controllable connection with any type of tractor propelled soil working implement and which is operative when connected with the implement to regulate its operating position in response to changes in draft force.

Still another object of this invention is to provide a tractor with an improved control system incorporating features of construction and combination affording parts controllably connectable with any soil working implement propelled by the tractor so as to effect regulating movements of the implement at a rate which varies as a function of draft force.

It is also an object of the present invention to provide a tractor with an improved control system and draft bar structure operatively combined to afford swinging movement of the draft bar structure about a transverse pivot axis disposed forward of and below the axis of rotation of the rear traction wheels and which affords a rigid connection with a rear attached implement whereby the draft bar structure and implement are vertically adjusted as a unit about said transverse axis in response to variations in draft force.

Still another object of this invention is to provide a tractor with an improved implement control means wherein a pair of lift mechanisms are mounted on the tractor in longitudinally spaced relation for operative connection with front and rear attached implements, and wherein a ram unit is pivotally supported for vertical swinging movement about a transverse axis rendering said ram unit selectively positionable for operative connection with either one or the other of said lift mechanisms, as desired.

A further object of the present invention is to provide a tractor with an improved implement control combination wherein front and rear mounted soil working implements are readily connectable with a draft force responsive element and a power control means operative to regulate the operating position of such implement or implements in response to changes in draft force.

Still another object of this invention is to provide a tractor with an improved control and hitch means suitable for regulating the operating position of a wheel supported implement coupled with said hitch means and carrying a power lift means remote from the tractor.

An additional object of this invention is to provide an improved controlsystem for tractor propelled soil working implements wherein features of construction and combination are directed toward affording simplification, positive regulation over a wide range, and increased utility as to its application.

The construction and operation of apparatus embodying the invention will become readily apparent as the disclosure progresses and particularly points out additional objects and advantages considered of special importance, and accordingly the present invention may be considered as comprising the various features of construction, combinations and/or subcombinations as is hereinafter more fully pointed out in the detailed description and appended claims, reference being had to the accompanying drawings in which:

Fig. 1 is a side elevation of a tractor rear attached implement combination embodying the invention with the left rear wheel removed and parts broken away for sake for clarity;

Fig. 2 is a partial plan view of the coacting portions of the drawbar and plow beam shown in Fig. 1;

Fig. 3 is a side view of the structure shown in Fig. 2 with parts disposed in partially detached position;

Fig. 4 illustrates a further embodiment of the invention showing the manner of applying draft regulation to a trailing implement;

Fig. 5 is still another embodiment of the invention illustrating the application of draft control to both front and rear mounted implements, with parts broken away and the left rear wheel removed to more clearly show the construction involved;

Fig. 6 is a view taken on line VI-VI of Fig. 5;

Fig. 7 is an enlarged plan view illustrating the manner of attaching the control unit to the tractor housing as indicated in Figs. 1 and 5 with a portion of the housing broken away to show the pum driving mechanism.

Fig. 8 is a vertical section taken on line VIII-VIII of Fig. '7;

Fig. 9 is a horizontal section taken on line IXIX of Fig. 8;

Fig. 10 is a section taken on line X'ne. of Fig. 8;

Fig. 11 is a section taken on line XI-XI of Fig. 8;

Fig. 12 is a section taken on line XII-XII of Fig. 10;

Fig. 13 is a schematic illustration of the control system with some parts shown in section to afford a better understanding of its operation;

Fig. 14 is a sectional view showing the relation of the main valve to the passages controlled thereby when the valve is in its implement lowering position;

Fig. 15 is a view similar to Fig. 14 showing the valve positioned to hold the implement in a raised or partially raised position with all pumps discharging liquid to the return passage means; and

Fig. 16 is a plan view of the single control lever taken on line XVI-XVI of Fig. 1.

Figs. 1 to 5, inclusive, of the accompanying drawings, illustrate three different applications of the present invention showing its use with soil working implements whether they be mounted on the front or rear of a tractor or drawn behind in trailing relation thereto. Referring particularly to Fig. 1 it will be seen that this figure illustrates application of the apparatus to a rear mounted plow. A conventional type tractor I. having a pair of rear driving wheels 2 and front dirigible wheels 3 for supporting a frame 5, has a moldboard plow 6 attached thereto in rear-- wardly extending relation with respect to the rear driving wheels. For attaching the plow to the tractor there provided a drawbar structure l and a support 8 therefor comprising a pair of laterally spaced plate members it fixed in dcpench ing relation to the under portion of the tractor, as by welding, immediately forward of and below the rear axle housing l l (note Fig. 6) a bifurcated lever l2 integrally fo med with a bearing means It adapted for positioning same between plate members Ill, and a. rod H5 extending through alined openings in lower portions of plate members It and through the bearing portion 95 of lever 12 thereby supporting the latter for swinging movement about rod I l. The lower portion of lever l2 has aligned transverse openings therethrough affording bearing means supporting a pivot pin ll: which in turn is connected to and supports the forward end of drawbar structure '5.

The upper portion of this lever, hereinafter called the draft regulating lever, has a spring biasing means acting on it to oppose the draft force applied to the lower end of the regulating lever through drawbar structure '5. This biasing means includes a spring seat ll rigidly fixed between upper forward portions of plate members H1 in transverse relation therewith, a compression spring l 8 positioned on seat H, and a plate member 26 fixed to the opposite end of the spring for engagement with forwardly projecting portions 2! of regulating lever 52. Thus it will be seen that draft force applied to the lower end of the regulating lever is opposed by the compressive force of spring l8 acting on the upper end of the lever.

Drawbar structure 1 comprises a bar member 22, a yoke 23 and pin 2i connecting the forward end of the drawbar with pivot pin it carried by the lower end portions of draft regulating lever i2 for vertical swinging movement of the drawbar relative thereto, and an opening in the rear portion of the bar member 22 for receiving a pin 34. In addition, there is provided a structure for guiding the swinging movement of the drawbar including a pair of vertical plate members 27 fixed to the under portion of rear axle housing H in depending laterally spaced and generally parallel r lation with respect to each other, a pair of similar strap members 28 having their upper ends pivotally mounted on coaXially aligned pins 36 carried by plate members 2l, a transverse guide bar 3i positioned between and carried by lower end portions of these strap members for rotation about a transverse axis, and a guide strap 32 fixed to the rear half of bar 22, as by bolts 3%, in overlying vertically spaced parallel relation therewith. G-uide bar 3i and guide strap 32 coact to afford guided swinging movement of drawbar l in both a horizontal and vertical direction. Openings 33 intermediate the ends'of similar strap members 28 are adapted for alignment with similar openings 35 spaced along the rear portion of plate members 2! for placing a pin 33 through selectively aligned openings to limit the lowering movement of the drawbar.

Referring more particularly to Figs. 1 to 3 it may be seen that implement 6 comprises a conventional moldboard plow 31 fixed to a forwardly extending beam 38 having a downwardly arched forward portion at. A bar member 4! curved similarly to portion 40 of the plow beam is disposed in laterally spaced relation thereto, being rigidly fixed to beam 33 by means of plate 32 and strap member 23. Plate 42 and member 413 interconnect bar 4| with arched portion 49 in a suitable manner such as by welding. In addition, a pair of vertically spaced strap members 45 and 46 are fixed between the rear portion of bar ll and adjacent beam portion 45 and have aligned openings 47 therethroughadapted for alignment with a similar opening '48 in guide strap 32. The forward ends of beam portion ll! and bar 4| have coaxially aligned openings 5:) therethrough for receiving a pin 5!. To attach implement 6 to drawbar structure "I the forward portion of the plow beam is placed so that plate member 42 underlies bar 22 with openings 41 coaxially aligned with opening 48 and pin 26 is placed therethrough. Pin 5| is placed through aligned openings 50 in the forward ends of bar 4| and beam portion 40 and rests against guide strap 32 (as shown in Fige 1) thereby preventing vertical swinging movement of plow 6 relative to drawbar structure I. The above described method of attaching implement 6 to drawbar structure 7 affords a rigid connection therebetween making the combined structure movable as a unit relative to pivot pin l6.

For lifting and lowering the implement, that is vertically swinging the implement and drawbar as a unit about the support for the latter offered by pivot pin it, there is provided a power lift means comprising generally a hydraulic pump 52 deriving power from the tractor engine 53, a ram 55 receiving fluid from the pump through a conduit 56, and a ram actuated lift mechanism 51 .operatively interconnecting the ram and the implement. The lift mechanism includes a pair of vertically disposed plate members 58 fixed'to and extending rearwardly from rear axl housing H in laterally spaced parallel relation with each other, a lift shaft 60 rotatably mounted in transversely aligned bearing means (not shown) carried by plate members 58 and a bellcrank lever secured to said shaft for turning movement there with and having one arm 6| pivotally connected with the rearwardly extending piston rod 46 of ram 55, and having its other arm 62 xtending.

rearwardly and pivotally connected with the upper end of a lift rod 63 which has its lower end pivotally connected with the underlying plow beam .38.

Referring again to drawbar support 8 shown in Fig. 1 it will be seen that draft regulating lever I2 is connected with the hydraulic pump unit 52 through a link 59 having a pivotal connection with the upper end portion of lever I2 and a lost motion (pin and slot) connection with an arm 54 extending from the pump control housing. Thus it is apparent that the drawbar is operatively connected with the hydraulic pump and it will b seen further along in the disclosure how this connection controls the action of the pump.

Looking now at Fig. 4 it will be seen that the present invention may be applied to a trailing implement, in this instance a two-bottom. plow 65. The drawbar structure 7 described above for the mounted plow is again'used and the twobottom plow is attached to the rear end of the drawbar by placing hitch pin 26 through vertically aligned openings in the implement hitch bar 66 which in turn are aligned with the opening 48 in bar 32 of the drawbar structure 7 thereby'affording lateral swinging movement of the implement relative to th drawbar structure. Implement hitch bar 66, preferably includes a conventional.

shock absorbing construction comprising relatively movable portions operatively interconnected through an interposed cushioning spring 68 adapted to absorb severe shocks caused by the implement striking rocks or the like. The rear portion of hitch bar 66 slidably engages a pair of vertically spaced strap members 1!] fixed to a second pair of vertical plate members H fixedly attached to the forward ends of the plow beams 12. forward ends by a U-shaped member l 3'having its transverse portion acting to separate the ends The plow beams are also joined at their.

of, beams 12. Pivotall attached to thistransverse portion of U-shaped member 73 anddisposed rearwardly between the two plow beamsis a ram .unit 15 receiving pressure liquid from pump 52 on the tractor through a conduit 16. Plow beams 12 extend rearwardly in laterally spaced relation and each terminates in a curved portion ll to which is rigidly attached a moldbcard plow 18 of a conventional type.

Intermediate portions of beams 12 fixedly mount two longitudinally spaced pairs of opposed plate members and 8| which are secured to the beams in depending relation thereto. These pairs of plate members mount pairs of aligned laterally spaced bearings receiving and supporting oppositely extending crank axles B2 and 83 carrying furrow and ground wheels 85 and 86, respectively. The forward crank axle 82 rotatably mounts a lever presenting a depending arm 81 connected with the forward end of a link 88 having its rear end pivotally connected with an upstanding arm 90 fixed on the horizontal portion of crank axle 33, and presenting an upstanding arm 91 pivotally connected to the adjacent end of rearwardly extending piston rod 94 of ram unit 15. The far side of crank axle 82 has a bracket 92 fixed thereto, the bracket extending upward therefrom and being pivotally connected with the lower forward portion of a notched quadrant 93 which in turn is pivotally connected with the rear portion of a coacting lever 95 carrying a latch rod 96 engageable with the notched portion of the quadrant. The rear end of lever 95 terminates in a depending portion 9'! pivotally connected with an upstanding arm 98 fixed to the far side end of crank axle 83.

And it should now be obvious that when lever 95 is latched to quadrant 93, a turning movement of crank axle 83 effects a similar turning movement of crank axle t2, and that when lever 95 is unlatched from quadrant 93, it may be moved relative to the quadrant thus effecting a leveling adjustment of furrow wheel crank axle 82 relative to the land wheel crank axle 83. Any turning movement of the lever (arms 9! and 81) relative to crank axle 82 effects an opposite turning movement of crank axle 83 through the medium of link 88 and arm 90. Consequently, upon admission of pressure liquid to ram unit 15, the piston rod moves toward the right thereby effecting a clockwise turning movement of lever arms Bland 81 and a counterclockwise turning (raising) movement of both crank axles 82 and 83. If, however, pressure fluid is withdrawn from the ram unit, the weight of the implements acts to rotate both crank axles in a clockwise direction thereby lowering the implement and moving the ram piston 89 to the left and into its cylinder.

Thus it will be seen that the hydraulic ram 15 may be readily controlled to effect relative vertical movement of the plows 18 and wheels 85 and 86 with respect to each other, which, in effect, raises or lowers the plows relative to the ground. Also, it should be apparent that a draft force is exerted on the tractor drawbar structure 7 and support 8 through movement of plow bottoms 18' draft regulating lever l 2, and the draft regulating link 59 interconnecting lever l2 and pump52 are allidentical with those described for Fig. 1 and" a description of these parts need not be repeated. However, it will be seen that triangular shaped plate members 08 have been placed in fixed relation on either end of pivot pin I carried by the lower end of draft regulating lever I2 thus affording means for connecting the front and rear implements in draft transmitting relation with the regulating lever. It will also be noted that in this case the ram unit I00 on the near side of the tractor has been swung forward for operating the front lift mechanism while the right hand ram unit IOI (shown in dotted lines) extends to the rear of the tractor for operating the rear lift shaft.

Mounted forward of the operators' station in overlying relation to pump unit 52 is a transverse lift shaft I02 supported on the tractor by strap members I53 fixed on either side of tractor frame 5; Rigidly fixed to the left end of lift shaft I02 in depending relation thereto is a lift arm I05 having pivotal connection with the piston rod I 06 of the left hand ram unit I00, And, pivotally mounted near either end of the lift shaft are forwardly extending links III each having pivotal connection with the upper end of a tool bar standard I08. These laterally spaced standards I08 carry a tool bar H0, positioned transversely beneath the tractor, to which a pair of bedders III are attached by means of clamps II2. At the lower end portion of each standard is a bracket H3 pivotally connected with the forward ends of a pair of rearwardly extending links H5 having their rear ends pivotally connected with pins I I0 extending outward from each of the triangular shaped plate members 98. Therefore, draft force on the front implements will be transmitted through links I I5 and plate members 98 to draft regulating link I 2. The near upper link I I! joining tool bar standard I08 With lift shaft I02 has :an arm I i8 depending therefrom in fixed relation thereto, the lower end of this arm being braced by strap member I extending upward to a forward portion of the link. Arm III! is positioned in edge abutting relation with lift arm I05 and therefore movement of the lift arm in a forward direction will urge arm I20 and link H! upward resulting in a lifting movement of standards I08, toolbar I III and bedders I I I.

' The rear lift mechanism 51 is identical with that described for the rear mounted plow and therefore a further description of this mechanism is believed unnecessary. The rear mounted implement includes a pair of conventional tool bar standards I'll (only one of which is shown) pivotally carried'at their upper ends by the rearwardly extending lift arms 62, a tool bar I22 positioned transversely with respect to the standards, a bedder I23 selectively positionable along the tool bar, and a pair of links I25 pivotally connected at their rear ends with the lower ends of tool bar standards I2I and at their front ends with pins I26 carried by'triangularly shaped plate members 98. Links I25 serve to transmit the draft force on the rear implement to the draft regulating lever Referring particularly to Fig. 6 it will be noted that the rear bedder has its draft transmitting link or draft bar I25, positioned on triangularly shaped plate member 93 at a point which is twice the distance from pivot pin I6 as the point of attachment for the front bedder draft bars H5. Therefore assuming the draft on all bedders is generally equal and proportional to the number of bedders employed, the resulting force on draft regulating lever I2 will be the same for a single 8 rear bedder I23 as it will be for the front two bedders III, since the effective lever arm for the single rear bedder is twice the length of the lever arm for the two front bedders.

Referring now to Figs. 1 and 7 it will be seen that the hydraulic pump unit 52 is attached to a hollow lubricant confining portion of the tractor drive shaft housing I30. A side Wall of drive shaft housing I30 is provided with an opening I 3| therethrough which exposes cam portions I32 on the tractor drive shaft I33. And a hydraulic pump and control unit 52 comprising a housing I34 is detachably secured to the side of drive shaft housing I30, as by bolts I36, in covering relation with respect to opening I3I therethrough (Fig. 7). The side of housing I34 opposing opening I3I in drive shaft housing I 30 is provided with marginal surfaces I31 for sealingly engaging the side wall surfaces of drive shaft housing I30 which bound opening I3 I. A hydraulic motor, in this case a single acting ram unit I38 (Fig. 13), is operatively connected with the pump and control unit housing I34 by a conduit I 40 for the flow of lubricant to and from ram I38. Ram piston MI is operatively connected with one arm of a bell crank lever I42 having a weight I53, representing an implement, attached to its other arm for actuation by the ram unit. As shown, the ram is in its expanded position and upon withdrawal of pressure fluid therefrom piston element IdI moves to the left and lowers weight M3. It will be understood that although the hydraulic system, particularly as shown in Figs. 7 and 13, is hereinafterdescribed for use with a single ram unit it may also be used with two ram units as shown in Fig. 5.

Referring also to Figs. 8 to 15, inclusive, it will be apparent that the side of pump housing I34 enclosing opening I3I in hollow structure I30 is provided with four inwardly extending parallel cylindrical chambers I45, I40, I4! and M8, chambers I45 to I41 being of equal diameter and chamber I48 having a materially reduced diameter. A compression spring I555 (see Fig. 10) is positioned within each chamber at the inner end thereof and each chamber includes a pump plunger I5! having a reduced inner end portion I52 disposed in guiding relation within the associated compression spring I50. The opening enclosing side ,of housing I34 is also provided with outwardly extending projections I53 having aligned holes therethrough receiving and fixedly mounting a shaft or rod part I54 disposed at a right angle with respect to the axes of pump plungers I5I and generally parallel to a plane therethrough.

And a plurality of cam followers I55, one for each pump, are pivotally supported on shaft part I54 for swinging movement relative thereto and relative to each other, the lower end portions of these followers being disposed between the outer ends of pump plungers I5I and the opposed cam portions I32 on shaft I33 thereby establishing an operative connection between power driven shaft I33 and pump unit 52 (see Fig. '7).

. Pump housing I34 is provided with an intake manifold (Fig' 12) passage I51! severally communicating with pump chambers M5 to I48 through intake passages I and communicating with the lubricant in hollow structure I35? through a main intake passage I53 terminating in the opening enclosing side of housing I34 below the pump plungers therein. Passage I includes an extending conduit portion I6I (see Fig. 11) projecting outward therefrom through the opening I3I and downward into the fluid confined in hollcw casing I36. Housing I34 is also provided with a; cylindrical valve chamber I62 which extends the'rethrough in spaced overlying relation with respect to pump cylinders M to I48 and in parallel right angle relation thereto. A plurality of passages I 63, one for each pump, severally connect the inner or discharge ends of the pump cylinders with longitudinally spaced portions of cylindrical valve chamber I62. In addition, housing I 34 includes a horizontal bore I65 which is disposed above valve chamber I62 in generally parallel relation thereto and which is connected therewith through a group of passages c ccrresponding in number to pump discharge passages I63. And in this connection it should be noted that'p'assages I66 communicate with valve chamber I62 in diametrically opposed relation to passages I63. Each passage IE5 is provided with a spring biased ball'check valve It! controlling the flow of fluid therethrough and into bore I65. This bore, which may be considered a manifold space, communicates at its right hand end (note Fig. 8-) with an outlet passage I55 for working fluid which terminates in an upwardly extending pipe" connection no provided with a suitable connec- L tor I II for coupling one or more ram hoses 56, I49 or the like thereto. Communication between outlet passage I58 and manifold space I65 is controlled by aspring biased ballcheck valve I72 preventing a back flow of fluid from passage I58 into the manifold space. In addition it should be noted that this discharge fluid passage I85 has a branch portion I13 on the discharge side of check valve I6! placing same in communication with the right hand end of cylindrical valve chamber I 62. v

Housing I34 is also provided with a main fluid return passage means comprising a horizontal bore I15 opening through the side suriacecf the housing closing the opening in hollow casing I3fl at a pointsomewhat below and to one side of intake conduit I 60 (Fig. 12), the inner end of return passage bore I75 communicates with a bore I16 at right angles thereto (Fig. 11) which extends nearly through the pump housing in gen-' erally parallel relation to and below valve chamber I62. This bore I16 is also disposed below pump chambers I45 to I48 and a plurality of passages III corresponding in number to pump discharge passages I63 place bore lit in communication with longitudinally spaced portions of cylindrical valve chamber I62, these passages IIi being disposed adjacent the pump cylinder chambers and the passages I63 severally connecting the discharge side of the pumps with longitudinally spaced portions of cylindrical valve chamber I62 as previously described. Another passage I'IB places main return passage bore H3 in communication with a right end portion of valve chamber I62 in longitudinally oiTset diametrically opposed relation with respect to the branch portion I73 of outlet passage 188.

In addition, housing I34 is provided with a cylindrical unloading chamber I89 extending therethrough in laterally spaced parallel relation with respect to cylindrical valve chamber I62 and on a horizontal level therewith. The left hand and of manifold bore I 65 communicates with the adjacent and of unloading chamber Its by means of a passage I 81 (Fig. 12) and an intermediate portion of this unloading chamber communicates with a horizontal discharge passage I82 (Figs. 9

and 10) opening through the side surface of the pump housing above the pump chambers.

The left end portion I83 of unloading chamber I is somewhat enlarged to provide an invernal shoulder I85 against which is positioned a disk type spring seat I86 having an opening it? therethrough. The opposite or left hand end of chamber portion Ice is closed by a cylindrical plug element I58 having an inner end portion I90 of reduced diameter projecting axially toward spring seat 536 in spaced relation with respect to the surrounding wall of chamber 589. The left hand end of plug member I88 is provided with a circumferential external groove I9I communicating with passage I8I leading thereto from manifold space I65. A transverse bore I92 corinects diametrically opposed portions of groove I9 I with acentral bore I93 which extends inwardirom transverse bore I92 and coaxially through the reduced portion Ifiil of plug member I88. Central bore I93 is enlarged from a point adjacent transverse bore le to the discharge side thereof to provide a seat for a ball valve I95 and to receivecylindrical valve element 29!. A cylindrical spring seat element I91 slidably surrounds the reduced end portion I50 of plug member I 88 and is provided at its open end with a peripheral flange I 98' slidably engaging the internal surface of unloading chamber portion I89, this flange also affording a seat for a compression spring 2st disposed between same and disk seat I86. The inner end of element I91 is provided with an internal recess forming a cylindrical seat 254 receiving the inner end of cylindrical valve element 2t which, through the action of spring 266, acts to hold this valve element and ball valve E85 positioned as shown in Fig. 9, that is, with the ball valve firmly engaged with its seat there by preventing a flcw of fluid therepast from manifold I65. And when thus positioned, it Will be noted that the flanged end of spring s'eat element I98 is spaced from the opposed inwardly facing shoulder presented by plug member I88. The reduced portion I90 of plug member I88 is provided with a transverse bore 292 therethrugh and is further reduced from its junction with the main portion of the plug member l B8 inward td a point beyond transverse bore 202 so as to provide an annular relief passage 203 which conimunicates with th spring housing portion of chamber I80 through one or more axial slots 2:85 in the peripheral edge portion of flange I98. Cylindrical valve element 2EII is also provided with an axial bore 2% extending from the ball valve end thereof approximately to its midpoint Where it communicates with a circumferential groove 2i)? adapted" to place the space between the end of valve element 2m and the seat for ball valve I55 in communication with the transverse bore 202 in plug member portion I96, thus providing a relief passage means for the space surrounding ball valve I85 when seated as shown in Fig. 9. Mso, the inner end portion of cylindrical spring seat element It! is provided with transverse bore 298 ther'ethr'ough for relief of any liquid accumulating'between same and the inner end of plug member reduced portion I951.

The left hand end of unloading chamber I88 and of cylindrical valve chamber I52 are closed by a cover plate 2H3 secured in end abutting rela tion to housing I34 by means of cap screws 2! I or the like. The right hand end of unloading chamber ms mounts a cylindrical spring seat M2 and is closed, as is also the corresponding end of valve chamber I62 by means of a cover plate 2I3 fixedly secured thereto by one of more cap screws 2 I5. A pressure responsive piston 2I6 is mounted in unloading chamber I80 in down stream relation with respect to spring seat disk 185 and is detachably connected with a movement transmitting rod 21? which extends coaxially through cylindrical spring seat 212 and through an aligned and somewhat enlarged opening are in cover plate 213. The outer or exposed end of control rod 2 i 'l is fixedly connected with and caries a stub shaft 220 which projects at a right angle therefrom in the direction of valve chamber H32 and in generally parallel relation to cover plate 213. A compression spring 221 is interposed between seat 2i2 and the opposed end of piston 2; in surrounding relation to piston rod 21?, this spring acting to move the piston toward the left as viewed in Fig. 9 in closed relation with respect to fluid return passage I82. It will be noted that the right hand end of unloading chamber 385 is provided with another fluid return passage 222 (Fig. 9) opening through the side face of the housing enclosing opening 534, this additional passage functioning to return any liquid tending to become trapped between piston 'Zlii and cylindrical spring seat 212.

Referring again to Fig. 8 it will be seen that a cylindrical liner comprising axially separable sections 225 to 229 is disposed in cylindrical valve chamber N52 with innermost section 229, that is, the section adjacent the right hand end of chamber I52, abutting cover plate 2E5. The opposite end section 225, that is, the section at the left hand end of chamber N52 is held in position by end abutting engagement with cover plate 2W. Cylindrical sections 225 to 229 are provided with circumferential external grooves 25! placing pump discharge passages I53 in communication with the check valve controlled passages I55. In addition each section is provided with transverse bores 232 (see also Fig. 9) placing the interior thereof in communication with the diametrically opposed pairs of passages I63 and use. Furthermore the end abutting portions of cylindrical sections 225 to 229 have parts thereof cut away and shaped to afford circumferential external grooves 233, rectangular in cross section, each of which communicates with the interior of the chamber formed by these sections through diametrically opposed transverse passages 234. The rectangular external passages 233 formed betwee end portions of cylindrical liner sections 225 through 229 communicate with passages I'H placing same in communication with the main fluid return passage H5. In addition, the innermost cylindrical section 229 is provided with two additional circumferential external grooves 236 and 258, groove 236 communicating with ram outlet passage H3 and with a transverse bore 23? placing diametrically opposed portions of this groove in communication with the interior of section 225, whereas groove 238 communicates with a passage I78 which in turn communicates with the right hand end of main fluid return passage I15. Groove 238 also communicates with the interior of liner section 229 through diametrically opposed transverse bores 240.

A cyindrical control valve 241 is positioned in the generally cylindrical chamber formed by the end abutting liner sections 225 to 229 and preferably this valve is formed by a series of separable cylindrical elements, 242 to 245 inclusive, disposed in end abutting relation, the end abutting portions of these cylindrical valve elements bein reduced to form annular spaces between same and the surrounding internal surfaces of the liner sections. In this connection it should be noted that the right hand or innermost valve element 245 comprises an intermediate reduced portion 24'! uniting enlarged cylindrical portions 248 and 255 which in turn terminate in reduced oppositely projecting end portions, the inner one of which abuts the reduced portion on adjacent element 244 and the other of which projects through a coaxial opening 25l in cover plate 2H3. The valve elements are held in end abutting relation for movement as a unit by means of a compression spring 252 seated on valve element 242 in surrounding relation to the reduced outer end portion thereof with its opposite end abutting the inner surface of cover plate 2H3. Movement of the valve element to the left as viewed in Fig. 8 may be adjustably limited through the medium of an inwardly projecting part 253 carried by cover member 240, this part having an internally threaded bore 255 extending therethrough in which is adjustably mounted a screw threaded element 255 having a reduced end portion 25'! disposed in coaxial abutting relation with respect to a similar projection on the adjacent valve element 242. The outer exposed end of element 255 is provided with a knurled adjusting knob 25S.

Referring more particularly to Figs. 9 and 12 it will be noted that the shaft 229 carried by control rod 2 ll operatively mounts a sleeve 259 having an enlarged portion 260 positioned in opposed engaged relation with respect to the reduced end portion of the innermost valve element 2 555 which extends through cover plate 2H. Shaft 225 also has connected therewith the upper end of a lever 251 through sleeve 259, thi lever having an intermediate portion thereof pivotally connected with a link 262 which in turn is pivotally connected with an arm 253 fixed to an inner end por tion of a shaft 255 rotatably supported in a bearing structure 265 carried by control linkage housing 25?. This housing is detachably secured in abutting sealed relation against cover plate M3 by means of suitable cap screws 269 or the like. And in this connection it should be noted that cover plate 213 is provided with a suitable opening 264 (note Fig. 8) which is aligned with and places main return passage bore H6 in communication with the interior of the linkage housing. Consequently housing 261 contains oil at a level conforming with that in drive shaft housing E32. The outer end of shaft 265 has a lever arm 268 fixed thereto which in turn may be connected through a. link 21!! (see Fig. l) with a suitable manually actuable control lever 2?! carried by the tractor steering column 212 and associated with a quadrant 273. The bottom portion of housing 26'! contain levers operatively connecting the lower end of lever ZBI with the draft regulating link 59 (shown in Figs. 1, 5 and 6). For example, a shaft 214 is rotatably supported in a bearing 215 mounted in the lower portion of housing 26? and has an arm 216 fixed to its outer portion affording connection with draft regulating link 59 through means of a pin 2H carried by the end of arm 276 which slidably engages a slotted end portion 218 of the draft regulating link, arm 21% carrying a lookout screw 279 engageabie with an internally threaded bore 284 in the lower portion of housing 261. The inner part of shaft 214 has fixed thereto an arm 280 having a pin 28! projecting transversely with respect to the end of the arm. Another shaft 282 is rotatably mounted in a bearing means carried by housing 25? and fixedly supports on its inner portion a cam lever 283 having a curved edge 285 thereof adapted for engagement by pin 28! onarm 280. The lower ems-s99 portion of cam lever-28.3 carries a transversely projecting pin 286 which slidably engages a slot 281 in the lower portion of lever 26!. It should be noted at this point that manual control lever 21I may be moved so as to shift the fulcrum for lever26l, that is the fulcrum 288 afforded by the connection of link 262 to an intermediate portion of lever 26L and thereby move the top of lever 26I relative to cover plate 2I3. Also, movement of draft regulating link 53, transmitted through the levers carried by the lower portion of housing 261, causes a swinging movement of lever 26! about the fulcrum point 288. More specifically, Spring 22-I in unloading chamber ids is relatively strong as compared with the spring 252 acting on control valve 2M and consequently piston 2 I6, control rod 2I1 and valve 2M tend to assume the positions shown in Figs. 9 and 12. Therefore, the above mentioned position of valve 2 control rod 2I1 and piston 2 I6 may be changed either (1) by moving manual control lever 21I to effect a shifting of fulcrum 288 in a direction away from cover plate H3 and thus pivot lever 26I about pin 236, or (2) by a movement of draft regulating link 59 away from pump housing 261 causing pin 28l to engage cam lever 283 and thus swing lever 26I in a clockwise direction (as viewed in Fig. 12) about its fulcrum 288. Either of these actuations of the common motion transmitting member 26I moves rod 2H and piston 2I6 toward the right as viewed in Fig. 12' which in turn compresses spring 22L As a result of such movement, spring 252 urges control valve 24! toward the right (note Fig. 9) and acts to maintain the reduced right hand end of this valve in engagement with roller 263. Movement of the valve in the direction just described, that is, toward the right is limited by engagement of the enlarged portion 250 of valve element 255 with cover plate 2 I3.

When operating with the parts positioned to obtain maximum lifting effect, that is, in their'full lift position, as shown in Figs. 8, 9 and 12, it will be, noted that the enlarged cylindrical portions of the valve elements 2E2 to 245, inclusive, close transverse bores 232 and that, therefore, the

pumps are severally connected with manifold space I65 through passages I63, external grooves 23I, and through check valve controlled passages I66. The liquid entering manifold space I65, asr suming all liquid has been drained from the ram I38, flow therefrom through check valve control passage I68 and quickly attains a pressure suificient to rapidly effect a weight lifting power stroke or expansion of the ram unit. When this occurs the pressure of the liquid in manifold space I55 continues to increase until the pressure attained is ufficient to unseat pressure relief ball valve I35 whereupon the check valve assembly comprising ball Valve [35 and cylindrical valve element 201 moves toward the right compressing spring 266 until valve element 20 I' opens transverse pressure relief bore 262. When this occurs, pressure fluid flows therethrough into annular space 263, then through the axial, passages 295 in the periphery of flange portion I98 of spring seat element I91, then into the spring housing chamber from which it flows through the opening I81 in disk spring seat I36 and then into the space between this seat and the head of piston 2I6. This pressure fluid then acts on piston 2 I6 and moves same toward the right thereby opening relief passage I 82, which is in communication with the source of oil in hollow structure 'I3'Il-and inlinkage. housing 261. This movement. of "piston. 246' 14 results in a movement of control rod 2I1 toward the right sufficient to bring the lower end of lever 26I into engagement with the side of cover plate 2 I3 which engagement limits the movement of the piston 2I6 and control rod H1 in this direction. As a result spring 252 causes control valve 241 to move toward the right in following engaged relation to roller part 260 and to the position indicated in Fig. 13. In this, the pump unloading position, the enlarged bore controlling portions of valve elements 242 to 244, inclusive, 'placetransverse bores 234 in the associated liner in communication with return passages i11 thereby severally connecting the discharge sides of pumps I45, I46, and I41 in communication with the main return passage bore I16. However, it should be noted that the enlarged portions 248 and 250 of valve element 2% remain in closed relation with respect to transverse bores 23s and 2-31, respectively, and therefore pump I48 continues to deliver fluid through circumferential groove 231 and into manifold space 55 through the associated check valve controlled passage I66.

It should be noted that the end area of cylindrical relief valve element 26I is considerably greater than the area of the passage controlled by ball valve I and that consequently it requires a relatively high pressure to effect an initial opening movement of these two valves; However, once an opening relation is established, the increase in effective area afforded by cylindrical relief valve element 20I operates to maintain the relief passage means open under a considerably reduced pressure head. Therefore, in

' the position just described, that is, the unloading position of main control valve 241, the three plungers in chambers I45, I46 and I41 are delivering fluid to the return passage means I16 whereas only one plunger, the one in chamber I43, is delivering fluid to the manifold space I65 and this fluid, assuming there is no appreciable leakage from the ram circuit, returns to the source through the relief means comprising passage I8I, bores I92 and- I93 in plug element I88; relief valve elements I95 and 201, transversebore 292 in plug element reduced portion iB'B, passages 203 and 205, the opening I81 through disk seat I83, and passage I82. In this connection it may be well to note at this time that although the enlarged cylindrical flow controlling portions of valve 241 are of substantially equal axial length, the reduced portion are of difierent axial lengths and in addition the axial spacing of the circumferential grooves 236, 23l, 233- and 238 and of the transverse bores or passages 232, 234, 231, 2 39am! 240 connected therewith vary somewhat as to their axial spacing so as to afford the above-mentioned regulation in respo se to an unloading movement of the control valve.

In the absence of excessive leakage, more particularly leakage through the flexible hose and the connections between such hose and the ram cylinder and pump housing, main-control valve- 24I will remain in its unloading position until either fulcrum 288 of lever 26'I is shifted by actu' ation 'of manual control lever 21!, or until a change in draft force moves regulating link 59 to cause cam lever 283 to swing lever 261 about its fulcrum 238 and with control valve 24I in its unloading position the hydraulic ram unit I38 will remain in its extended weight lifting position. However, if for any reason the pressure in m'an-ifoldspace I65 should decrease below that necessary to hold ballvalve I95 and'cyl-indrica'l 1' relief valve 2M in their "passageopening positions (note Fig. 13) these valves will close the relief passage means I81 and, as the liquid drains from the space ahead of piston 2I6, spring 22I will move piston H6 and control rod 2I'I to the left thus repositioning the main control valve 2M to connect all pumps to manifold space I65, this initial position of main control valve 24| being determined, as previously indicated, by the position of manual control lever 21].

However, if with the control valve 24! in either its full lift or unloading positions previously described it becomes desirable to lower the weight,

all that has to be done is to move manual control lever 2H to a lowering position, that is, in a direction effective to shift fulcrum 288 for lever 26! away from cover plate 213 a distance sufficient to permit spring 252 to move main control valve 241 to the right until the discharge sides of all pumps and the ram relief passage means (232, 239 and 23'!) are in communication with a movement of valve 24I to its lowering position 1 shown in Fig. 14 rapidly drops the implement onto the ground. If, however, it is desired to gradually lower the weight or implement onto the ground, this can be readily accomplished simply by moving main control valve 24! so as to just barely open the passage means 23'! placing the ram relief passage I13 in communication with the return passage means I18 and H5. And if in this connection it should be desired to place all pumps in communication with the return passage means I'IB through passages I11 and yet retain the ram in its extended position, this can be readily done by manually shifting fulcrum 288 of lever 26I so as to position main control valve 24! as indicated in Fig. 15. When this positioned, it will be seen that the enlarged portion 250 of the cylindrical control valve section 245 closes the transverse bore 23'! to prevent placing the ram relief passage I13 in communication with the return passage means I18 and H6.

It should also be obvious that in addition to the various positions of the main control valve 24I hereinbefore described, the valve may be also positioned by a manual shifting of the fulcrum 288 for lever 26I so as to, if desired, effect a ram expanding action by connecting the discharge sides of two or more pumps with the check valve control passages I66 connecting same with manifold space I65. And while it is normally intended that the enlarged cylindrical portions of main control valve 2M will be positioned so as to either open or close the radially extending transverse bores or passages 232, 231 and 239 placing the circumferential external grooves 235 and 23| in communication with the interior of the valve chamber formed by liner sections 225 to 229, inclusive, it should be obvious that the valve elements may be positioned so as to only partially open one or more of transverse passages 232, 231 and .239. Furthermore, it should be apparent that while the particular arrangement of the passages and valve elements herein shown for purposes of illustration constitutes a preferred embodiment of the present invention, other arrangements can be readily made as desired simply by '16 changing the actual spacing of the control passages 232, 23? and 239, circumferential grooves 236, 238, 23I and 233 and/or the axial length of the enlarged passage controlling portions of valve elements 242 to 245, inclusive.

Referring again to Figs. 8, 9 and 12, it will be apparent that the position of valve 2M determines whether the weight, implement or device connected with ram unit I38 is to be raised, lowered or held in a selected position and, if the weight is being either raised or lowered, the rate of movement thereof. In addition, it should be apparent that irrespective of the rate of lift, as soon as the pressure head on the pump attains a predetermined value, the relief passage means 58E is immediately opened through the coaction of ball valve E95, cylindrical valve element Zfil, and piston 2 i5. Furthermore, if the lift position of valve 2 1! is such that more than one plunger is delivering fluid to manifold space 565, opening of the relief passage means I8! results in an immediate movement of this valve to its unloaded position shown in Fig. 13. In any case, once the relief passage means is initially opened in response to attainment of a pressure sufiicient to unseat ball valve itii, it is held open by the then dominating action of cylindrical valve element 263! thereby effecting a material reduction in pressure head, as previously described. In the operation of hydraulic motors, and more particularly rain units, a high initial pressure is usually required to overcome the inertia of the load and/ or effect a desired acceleration thereof. And in order to rapidly eifect a complete power stroke, the capacity of the liquid supplying pump must be such as to quickly establish and maintain an effective pressure for any rate of ram displacement. However, upon completion of a load shifting or moving power stroke, generally only a fraction of the initial pressure is required to retain the load in the position to which it has been shifted. For example the operation of a ram system such as herein disclosed, particularly if applied to various types of agricultural implements, may require a power stroke pressure of as much or more than 3500 pounds per square inch and a load retaining pressure of only 1200 pounds per square inch. In addition, if it were possible to maintain perfect seals, particular reference being had to the seating of valves till, i'i2 and 95 and the sealing action of the enlarged portions of main valve sections 2:22, M3, 244 and 255, operation of the pump means could be discontinued providing ram operation is infrequent. Usually, however, the ram is frequently operated and its operation is nearly continuous when applied as a draft regulating device. Consequently, the feature of eliecting a reduction in pressure head as previously pointed out is important in that it not only reduces pump load and heating, both of which are detrimental to pump life, but it also efficiently compensates for leakage and conditions the system for an immediate response to load requirements.

Referring generally now to Figs. 1 and 16 the operation of apparatus embodying the present invention will be described with specific reference to other figures being made as the description progresses. Assuming that the attached plow 6 is in transport or fully raised position to begin with, the action of the apparatus will be described as the plow is lowered to the ground and assumes a soil working position. With the implement thus positioned, valve MI is in its unloaded position (Fig. 13) and the lower end of lever 26I will have on the tractor is adapted for lifting the soil working implement 5, and a plurality of power transmitting means, represented in the embodiment of the invention by pump plungers ll, operatively interconnects a power source, shown as engine 53 on the tractor, and mechanism 5'? for simultaneous actuation of the latter. A movable control part 24! is operatively associated with the power transmitting means i5l for progressively varying the number of power transmitting means effective to actuate mechanism 51, and additional control means comprising the linkage elements Ziil, 283, 28!, 230, 2% and 218 connect support member 2 with control part or valve 26! and render the latter operative to increase the number of pump plungers i5! effective to actuate mechanism 57 and thereby the rate of lift in accordance with the extent support member or lever l2 moves longitudinally in the aforementioned direction. In the embodiment of the invention shown, mechanism El is actuated by ram 55 which is subjected to hydraulic pressure from plungers 153, the flow from which is controlled by valve 2M so that the discharge from the individual pumps may be progressively directed either to ram 55 or back to the source of liquid in housing lfifl.

It is sometimes desirable to dispense with draft regulation in performin certain operations and, referring again to Figs. 9 and 12, it should be obvious that arm Zlt can be locked or secured in fixed relation to housing 2%? simply by moving arm. Elli to a position wherein screw 2'39 is aligned with bore 23% in housing 2t? and engagin the screw in position within the bore. And since it will be noted that pin Ell is in the upper limit of the slotted end portion 2% of the draft regulating link it should be obvious that any further draft induced movement of this link will merely shift slotted end portion iill relative to the now fixedly positioned pin 211. For readily turning screw 219 a knurled knob 292 is provided, and spring 2% is positioned between knob 292 and arm .Zlii for urging screw 2T9 outwardly and thus preventing displacement of same due to vibration of the tractor.

It should also be obvious that the construction and combination of parts herein disclosed responds solely to draft induced force and therefore functions to regulate the operating position of a soil working implement independent of the weight of the implement and independent of effecting a change in its angular position relative to the soil. This is another important feature in that it not only renders the apparatus applicable for regulating the operating position of all types of implements, but it avoids effecting such regulation as an incident to a change in the angular relation of the implement relative to the ground, the latter being objectionable as it is conducive to over regulation or huntin and requires a special hitch means.

' Another feature of considerable importance is that the rate of lifting eifected by a change in draft induced force and thereby the responsiveness of the apparatus varies as a function of the rate of increase in such force since if the draft induced force rapidly increases, more pumps are quickly brought into action. In addition, the apparatus herein disclosed affords means for effect ing automatic regulation of the operating position of an implement in response to variations in draft induced force and it also affords means whereby the automatic regulation may be readily dispensed with when and if desired and which 2b will then aiford an increment adjustment of implement position.

And it should be obvious that although the automatic draft regulation of an implement has been described with particular reference to a rear mounted implement such as is shown in Fig. 1, the operation is essentially the same for implements mounted on or attached to the tractor as illustrated in Figs. 4 and 5. The latter illustrations clearly indicate that the apparatus is applicable to all types or" tractor propelled implements. And it should therefore be understood that it is not intended to limit the invention to the exact constructions and combinations herein shown and described as various modifications within the scope of the appended claims may occur to those skilled in the art.

It is claimed and desired to secure by Letters Patent:

1. In combination with a tractor having a power source, a drawbar support member operatively mounted on said tractor for limited fore and aft movement longitudinally thereof; a re silient means carried by said tractor in a position resisting said movement of said support member in the direction it would normally be: urged by the ground penetration of a soil work-v ing implement having a propelling connection therewith; a mechanism operatively mounted on said tractor in a position adapted for lifting a. soil working implement having a propelling connection with said support member; a plurality of power transmitting means operatively interconnecting said source and said mechanism for simultaneous actuation of the latter; a movable control part operatively associated with said power transmitting means for progressively varying the number of power transmittin means effective to actuate said mechanism; and additional control means operatively connecting said support member and said control part and rendering the latter operative to increase the number of said power transmitting means effective to actuate said mechanism and thereby the rate of lift in accordance with the extent said support member moves longitudinally in said direction.

2.1n combination with a tractor havinga power source; a drawbar support member operatively mounted on said tractor for limited fore and aft movement longitudinally thereof; a resilient means carried by said tractor in a posi tion resisting said movement of said support member in the direction it would normally be urged by the ground penetration of a soil working implement having a propelling connection therewith; a mechanism operatively mounted on said tractor in a position adapted for liftin a soil working implement having a propelling connection with said support member; a plurality of power transmitting means operatively interconnecting said source and said mechanism for simultaneous actuation of the latter; a movable control part operatively associated with said power transmittin means for progressively varying the number of said transmitting means effective to actuate said mechanism; a manually shiftable element operatively connected with said control part for moving same so as to selectively vary the number of said power transmitting means operative to effect a lifting actuation f said mechanism; and additional control means operatively connecting said support member with said control part and includin a connection with said manually shiftable element rendering said 21 additional means operative, whenever said manually shift'able element is in a position rendering less than all of said power transmitting means operative to actuate said mechanism, to

movesaid control part to increase the number of member in the direction it would normally be urged by the ground penetration of a soil working implement having a propelling connection therewith; a mechanism operatively mounted on said tractor in a position adapted for liftin a soil working implementhaving a propelling connection with said support member; a plurality of power transmitting means operatively interconnecting said source and said mechanism for simultaneous actuation of the latter; a movable control part operatively associated with said power transmitting means for progressively varying the number of said power transmitting means effective to actuate said mechanism; additional control means operatively connecting said support member and said control part and rendering the latter operative to increase the number of said power transmitting means efiective to actuate said mechanism and thereby the rate of lift in accordance with the extent said support member moves longitudinally in said direction; and a manually shiftable element operatively connected with said control part so as to move said control part to a predetermined position renderin said additional means and said support member inoperative to cause actuation of said mechanism.

4. In combinaation with a tractorhaving a power source; a drawbar support member operatively mounted on said tractor for limited fore and aft movement longitudinally thereof; a resilient means carried by said tractor in a position resisting said movement of said support member in the direction it would normally be urged by the ground penetration of a soil working implement having a propelling connection therewith; a mechanism operatively mounted on said tractor in a position adapted for lifting a soil working implement having a propellin connec tion with said support member; a plurality of power transmittin means operatively interconnecting said source and said mechanism for simultaneous actuation of the latter; a movable control part operatively associated with said power transmitting means for progressively varying the number of said transmitting means efiective to actuate said mechanism; a manually sh-iftable element operatively connected with said control part for moving same so as to selectively vary the number of said power transmitting means operative to effect a lifting actuation of said mechanism; additional control means operatively connecting support member with said control part, and including a connection with said manually shiftable element rendering said additional means operative, whenever said manu ally shiftable element is in a position rendering less than all of said transmitting means operative to-actuate said mechanism, to move said control part to increase the number of said power transmitting means effective to actuate said mechanism and thereby the rate of lift in accordance with the extent said support member moves longitudinally in said direction; and. a lookout element associated with said additional means and selectively positionable to render said longitudinal movement of said support member ineffective to move said control part.

5. In combination with a tractor having a power source; a drawbar support member operatively mounted on said tractor for limited fore and aft movement longitudinally thereof; a resilient means carried by said tractor in a position resisting said movement of said support member 'in the direction it would normally be urged by the ground penetration of a soil working implement having propelling connection therewith; a mechanism operatively mounted on said tractor in a position adapted for lifting a soil working implement having a propelling connection with said support member; plurality of power transmitting means operatively interconnecting said source and said mechanism for simultaneous actuation of the latter; a movable control part operatively associated with said power transmitting means for progressively varying the number of said transmitting means effective to actuate said mechanism; a manually shiftable element operativel connected with control part for moving same so as to selectively vary the number of said power transmitting means operative to effect a lifting actuation of said mechanism; and additional control means operatively connecting said support member with said control part and including a connection with said manually shiitable element rendering said additional operative, whenever said manually shift-able element is in a position rendering less than all of said power transmitting means operative to actuate said mechanism, to move said control part to increase the number of said power transmitting means effective to actuate said mechanism and thereby the rate of lift in accordance with the extent said support member moves longitudinally in said direction, said manually shiitable element and said support member being connected with said control part through a common motion transmittmg member movable by an actuation of said menu ally shiftable element to a position having a lost motion connection with said control part whereby a preselected increase in said work load is necessary before a movement of said so port member eifects a corresponding movement of said control part.

6. In combination with a tractor; a drawbar support member operatively mounted on said tractor for limited lore and aft movement longitudinally thereof; a resilient means carried by said tractor in a position resisting said movement of s support member in the direction it would normall be urged by the ground penetration of a soil working implement having a propelling oonnection therewith; a source liquid; a hydraulic pump deriving operating power from said tractor, said hydraulic pump including a plurality of pumping elements receiving liquid from said source; a lift mechanism operatively mounted on tractor for connection. with a soil workin implement having a propelling connection with said support, said mechanism including a ram unit receiving pressure liquid from said pump; a control valve positioned on the discharge side of said pump and being operatively'movableto increase or decrease the-num- 23 her of said pumping elements delivering liquid to said ram unit; and additional control means operatively connecting said support member with said control valve and rendering the latter operative to change the number of pumping elements delivering liquid to said ram unit and thereby the rate of ram displacement in accordance with the extent said support member moves longitudinally in said direction.

'7. In a tractor having a rotatable rear trac tion means; the combination comprising: a drawbar pivotally attached to a support member operatively mounted on said tractor for fore and aft swinging movement about a transverse pivotal axis disposed forward and below the axis of rotation of said rear traction means, said drawbar being thus supported for limited movement longitudinally of said tractor; means resisting such movement of such drawbar as may result from an increase in an implement induced work load thereon; a source or liquid; a hydraulic pump deriving operating power from said tractor, said hydraulic pump including a plurality of pumping elements receiving i uid from said source; a lift mechanism adapted for operative connection with an implement coupled with said drawba-r, said mechanism including a ram unit receiving pressure liquid from said pump; a control valve movable to increase or decrease the number of said pumping elements delivering liquid to said ram unit; and additional control means operatively connecting said drawbar with said control valve and rendering the latter operative to change the number of pumping elements delivering liquid to said ram and thereby the rate of ram displacement in accordance with the extent said drawbar structure moves longitudinally in response to an increase in the implement induced work load thereon.

8. In combination with a tractor: a drawbar operatively mounted on said tractor for limited fore and aft movement longitudinally thereof; a resilient means carried by said tractor in a position resisting said movement of said drawbar in a predetermined direction; a soil working implement coupled with a rear portion of said drawbar and being thereby disposed in trailing relation behind said tractor, said implement exerting a working load on said drawbar which acts in opposition to said resilient means; a source of liquid; a hydraulic pump deriving opera-ting power from said tractor, said hydraulic pump including a plurality of pumping elements receiving liquid from said source; a lift mechanism comprising a ram unit operatively associated with said implement to raise the soil working elements thereof relative to the ground in accordance with the rat of ram displacement; a control valve movable to increase or decrease the number or said pumping elements delivering liquid to said ram unit; and additional control means operatively connecting said drawbar with said control valve so that a longitudinal movement of said drawbar, resulting from a change in the work load exerted thereon by said implement, proportionally shifts the position of said control valve to change the number of pumping elements delivering liquid to said ram unit and thereby the rate of ram displacement.

9. In combination with a tractor having a rear traction means and an engine connected in driving relation to said traction means; a lever pivotally mounted on the tractor forward of and below the axis of rotation of said rear traction means for swinging movement longitudinally of the tractor; a drawbar pivotally connected with said lever for vertical swinging movement relative thereto, said drawbar and lever being movable in unison longitudinally of the tractor; a soil working implement connected in draft force transmitting relation to a portion of said drawbar remote from said lever; a source of liquid; a hydraulic pump deriving operating power from said tractor, said hydraulic pump including a plurality of pumping elements receiving liquid from said source; a lift mechanism mounted on said tractor and including a ram unit receiving pressure liquid from said pump, said ram unit being operatively connected with said implement to raise the latter in accordance with the rate of ram displacement; a control valve movable to increase or decrease the number of said pumping elements deliverin liquid to said ram unit; and additional control means operatively connecting said drawbar with said control valve so that a longitudinal movement of said drawbar, resulting from a change in the work load exerted thereon by said implement, proportionately shi ts the position of said control valve to change the number of pumping elements delivering liquid to said ram unit and thereby the rate or" ram displacement.

10. In combination with a tractor having a power source and a rear traction device for propelling same; a drawbar supporting lever operativelymounted on said tractor for limited fore and aft sw nging movement longitudinall thereof; soil working implements operatively mounted on said tractor for both vertical and longitudinal movement through means including propelling bars extending fore and aft from and connecting said implements with said supporting lever so as to exert an implement induced work load on the latter; a resilient means carried by said tractor in a position resisting said movement of said supporting lever in the direction it would normally b urged by the ground penetration of said soil working implements having propelling connections therewith, said implements being disposed in front and to the rear of said traction device; a source of liquid; a mechanism operatively mounted on said tractor in a position adapted for lifting said soil working implements having propelling connections with said supporting lever; a plurality of power transmitting means comprising a hydraulic pump including a plurality of pumping elements receiving liquid from said source of liquid and including a pair of ram units receiving liquid from said pump and being operative to interconnect said power source and said mechanism for simultaneous actuation of the latter; a control valve operatively associated with said power transmitting means and movable to progressively increase or decrease the number of said pumping elements efiective to actuate said mechanism; and additional control means comprising a linkage operatively connecting said supporting lever and said valve so as to move the latter in response to and proportional to the extent said supporting lever moves longitudinally in said direction to thereby increase the number of pumps effective to actuate said mechanism.

11. In combination with a tractor having a power source and a rear traction means for propelling same; a drawbar supporting lever operatively mounted on said tractor for limited fore and art swinging movement longitudinally thereof soil working implements operatively mounted on said tractor for both vertical and longitudinal movement relative thereto through means including propelling bars extending fore and aft from and connecting said implements with said sup- 25 porting lever so as to exert an implement induced work load on the latter; a resilient means comprising a biased device carried by said tractor in a position resisting said movement of said supporting lever in the direction it would normally be urged by the ground penetration of said soil working implements having propelling connections therewith, said implements being disposed in front of and to the rear of said traction means; a source of liquid; a mechanism operatively mounted on said tractor in a position adapted for lifting said soil Working implements having propelling connections with said supporting lever; a plurality of power transmitting means comprising a hydraulic pump including a plurality of pumping elements receiving liquid from said source of liquid and including a pair of ram units receiving liquid from said pump and being operative to interconnect said power source and said mechanism for simultaneous actuation of the latter; a control valve disposed on the discharge side of said pump and being movable to progressively increase and decrease the number of said pumping elements effective to actuate said mechanism; a manually shiftable element operative to con- 7 trollably move and retain said control valve in a preselected position; and additional control means comprising a linkage operativelyinterconnecting said supporting lever, said manually shiftable element and said control valve for moving said control valve away from said preselected position and relative to said manually shiftable element in accordance with the extent said supporting lever moves longitudinally in said direction.

12. In combination with a tractor having a power source comprising an engine and a rear traction means connected in driven relation with said engine; soil working implements operatively mounted on said tractor to the front and to the rear of said traction means for independent movement both vertically and longitudinally relative to said tractor; a drawbar supporting lever pivotally mounted on said tractor for limited fore and aft swinging movement longitudinally thereof; implement propelling bars extending fore and aft from and operatively connecting said implements with said supporting lever so as to exert an implement induced work load on the latter; a resilient means comprising a biased device carried by said tractor in a position resisting said movement in the direction it would normally be urged by the ground penetration of said soil working implements having propolling connections therewith; a source of liquid; separate lift mechanisms operatively mounted on said tractor and connected with said soil working implements for individually raising and lowering same; a plurality of power transmitting means comprising a hydraulic pump deriving operating power from said engine and including a plurality of pumping elements receiving liquid from said source of liquid and including a pair of rain units receiving liquid from said pump and being operative to interconnect said power source and said lift mechanisms for simultaneous actuation of the latter; said ram units being pivotally supported on said tractor for vertical swinging movement about transverse pivot axes with one of said axes disposed approximately midway between longitudinally aligned and spaced parts of said separate lift mechanisms whereby one of said ram units is selectively connectable with either of said mechanisms; a control valve operatively associated with said power transmitting means and selectively positionable for progressively varying the number of pumping elements delivering pressure liquid to said ram units to thereby vary the rate of ram displacement; and additional control means comprising a linkage operatively connecting said support lever and said control valve so that a work load induced movement of the former actuates said valve to increase the number of pumping elements delivering liquid to said ram units in accordance with the extent said supporting lever moves longitudinally in response to an increase in the work load exerted thereon by said implements.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,279,792 Ulevog Sept. 24, 1918 2,074,618 Roeder Mar. 23, 1937 2,103,530 Henry Dec. 28, 1937 2,356,231 Ferguson Aug. 22, 1944 2,368,125 Evans Jan. 30, 1945 2,394,210 Sherman Feb. 5, 1946 2,405,334 Silver Aug. 6, 1946 2,412,362 Silver Dec. 10, 1946 2,430,597 Acton Nov. 11, 1947 2,611,306 Strehlow et al. Sept. 23, 1952 2,611,307 Strehlow et al Sept. 23, 1952 FOREIGN PATENTS Number Country Date 253,566 Great Britain June 14, 1926 

